1. Field of the Invention
The present invention relates generally to hydraulic dampers for vehicular suspension systems. In particular, this invention is concerned with a non-steerable shock absorber having a reciprocating piston and piston rod mounted in a fluid-filled inner cylinder which provides variable damping dependent upon the rotation of a road wheel assembly.
2. Brief Description of the Related Art
Hydraulic dampers, including shock absorbers and struts, are well-known in vehicular suspension systems. The rate of damping of a hydraulic damper is often tuned by a piston valving assembly and/or a base valve assembly. Conventional piston and base valving assemblies employ various disk packs and spring-biased blow-off elements. During compression and rebound strokes of a damper, fluid flow through these valving assemblies determines the type of damping characteristic produced by the strut.
Many constructions have been developed to provide variable damping. In particular, it is well-known to provide a rotatable plate in a piston valving assembly to change the size of an orifice or other element to alter fluid flow through a piston valving assembly. Oftentimes, an electric motor is used to rotate a valve plate in a piston assembly.
The art continues to seek improvements. It is desirable for a variable non-steerable shock absorber to provide different damping rates for different driving conditions. In particular, during straight-ahead motion of a vehicle, a "soft" ride increases the comfort of passengers. During a steering motion when the vehicle wheels are turned, a "firm" damping rate provides greater control of the vehicle. It is desirable to provide a shock absorber which can vary the damping rate dependent upon these driving conditions.